dunham



Patented Feb. 13, 1923.

mi e

niente e. Dumm-ini, or fr COMPANY, rnoonronarnn,

TELEPHONEflElKCHANGrE S'r STEM.

Application filed 7, 1919. Serial Noltl?,

lle it known that l' llena' (i. lionel-ini, a citizen oft the llnitcd italis.. residing' :it linwtllerne, in the county oi. liasseic`r Acitate ot New loi have invente/l certain new and use'lful linproveniente in l`elephoin-lile change Systeins oil which the 'tollowingil is a tull, clear` concise, and exact description.

This invention relates to improvements in telephone exchange systems and has par ti cular reference to line switch circuits theretor. l

llercto'lore it hasbeeu customary to provide a line switch with a cutoff relay which operates, upon the seizure ol a trunln to extend a calling line to a selector switch7 whereupon the seized line or trunk is held busyby relays atI saidselector switch. ln systems ot this character there is a slight time interval between. seizure of the switch and the operation o the relay at the seized switch which renders the line busy.

An object of the present invention is to avoid the time interval which exists between the actual seizure of a trunk or line and the application ofa busy condition thereto.

A. feature to provide means at the line switch for holding a seized trunlr busy until the calling subscriber transmits impulses to operate a succeeding; switch.

The inventive idea involved is capable ot receiving a variety of expressions seme o' which tor the purpose et illustrating the invention, are shown in the aecompanyingg drawings; but it is to be expressly undere stood that said drawings are employed .merely Yfor the purpose et 'Facilitating the descriptionol the invention as a whole and not to define the limits thereof, reference being had to the appended clain'is for this purpose.

In. the drawings, l illustrates diagramrnatically a circuit for a line switch having no normal. position, Fig. 2 is a similar View oil? a circuit in which the switch is returned to normal at the termination of a call.

Referring to the drawings and more particularly to Fig. l, when. a subscriber at substation l removes his receiver from its switchhookV to initiate a call, a circuit is closed for line relay 2 extending trom grounded battery7 right I winding' oi said relay1 bach: contact and inner armature ot cutoH;A relay Bg apparatus at substation l.

lett winding` of relay 2 and. bachi contact and outer armature ot rel 3 to groiilnd. Relay v? energizes and by attracting its lett armatrue applies ground to conductor i leading to the test terminal 5 ot a connector multiple, thus preventing seizure of the line et substation l. By attracting its right armature, relay 2 short-circuits cutoil relay 3 which remains in this conditi on until relay i3 deenergizes in response to the first impulse transmitted from the substation l.

Iii the brushes (i, 7, 5i and 9 ot the switch are resting' iuion the terminals et an idle trunk, an energizing circuit tor relay l() will be established extending from grounded. battery, windingn armature and back contact of motor magnet lil., the contacts oit the right armature ot relay 2, winding o'l relay 1.0, conductor t and left armature and iront Contact of relay 2 to ground. `Motor magrnet 11 is adjusted so as not to operate when in series with either or both relays 3 and l0. By attracting its upper armatures re lay i0 connects the calling line tothe brushes 6 and 7 but the line is not extended to the next succeeding' switch owing to the short circuiting of cutol" relay 3 by the line relay. Thenround at lelt armature oit relay 2 is now extended through the trent contact and inner lower armature oli relay l0 and brush 8 to the test terminal ot the seized trunlu thus holding` this trunk busy 'until relay is deenergized. Relay 10 is then locked up through, its front contact and inner lower armature. llllhen the subscriber atsubstation l. operates the impulse sending; device l2 the circuit for line relay Q is opened and this relay then deenergizes. Release of relay 2 opens the short circuit for relay 3 which then energizes over the circuit extendingr from grounded battery7 winding, armature and back contact oiE motor magnet 11, winding; of relay 3,`winding, front contact and inner lower armature oit relay l() and brush. 8 to `ground upon the busy test terininal of the seized selector switch. Euer girtation or relay 3 extendsthe calling line through the inner armature and front con tact thereoit5 the upper armatures oi. relay 1.0 and brushes 6 and 7 to the trunk of the succeeding switch.

Let it now be assumed that the brushes of the switch are in yenga .gement with the energized as before cutoff relay 3 is again "terminals et busy trunlr. lWhen relay 2 is short-circuited Aand the ground at the lett armature ot relayI 2 .is extended to one end of t-he winding of relay 10. The other end of Isaid winding is also grounded from the front contacts 'and right armature ol relay 2, back Contact and inner lower 'armature' of relay 10 and brush 8 to ground upon the busy terminal.. This circuit being independ ent ofthe ywindings `of `-`either ot'the relays 3,01' 10V willjjcau'se'the motor magnet to operate andstep-the brushes of the switch untilthe terminals ot' an idle. trunk are en- `.gaffechwhereupon -the operation "of the switch. is the same as previously described. {iff-'the service of substation 1 is restricted, the -front contact of the outer lower art'mature of relay 10 is connected to brush 9,

as shown,-s"that upon the release otre- -lay 2 `when the first -impulse is transmitted, the ground upon the test 'terminal of the l seized 'trunk'is extended throl'i'gh brush 8 rinner 'flowerarmature and front contact of relay 10,"conductor l. lett' armature and back Contact of relay 2, outer lower karmay ture and trontcontact of relay '10 and vided at the latter switch brush" 9 tov the succeeding switch. Means (not shown.) well known in the art are protor preventing the 'establishment ot' the call initiated at the substation. One method of attaining this yresult is shown in the ,luttent to iVilliarns,"No. 1,355,635n issued October 12,1920.

yAt the termination ot a successful call, the release [otthe selector switch connected to the line switch removes ground from the-terminalengaged ,brush 8 and thus opens-'thc locking circuit for relay 10 which then releases. n:Relay 3 which also maintained inthis Icircuit *thereupon releases and the switch is then in conditionf to extend another call, the brushes thereotl remaining inthe position assumed when the idle .trunk was round.

' ,0n incoming calls to `substation 1, it' the Vlin'e .idle andthe'connection is automatic,

v l' et, left armature and` o0 a gro nd will@befe'xtended from a connector switch* through test. 'terminal 5. conductor `v back contact of relav 9 O relay 10Wl1dina Oflcutff relay 3, back `lcontact, V`arxrrature and windingof 'motor magnet llto `grminded battery. Cutoff re- 'lay 3` energines in vthis circuit and y prevents the establllshmentoot the 'energizing circuit ythrouirh its lett winding.

the test terminal of 'the seized `outer lower armature and back contact 'for line relay lt the connection manual, the cutoff relay 3 is olfieia'ted in the same manner by ground extending troni Contact 13, over the previously described circuit when an operator inserts a plug into jack 14. This ground on contact 13 is extended to terminal 1 and thus provides a busy test for the called line.

Referring now to Fig. :2, when a call is initiated at substation 11, line relay l5 is energized by a rirbuit extcndiluir troni grounded battery, right windingol' said rclay, inner upper alternate contactof cutoff relay 16, yback contact and left armature oi? relay 15, substation apparatus and outer upper alternate contact of relay 16 to ground. Relay l5 enernlzes, whereupon the energizing cirruit therefor will extend ln attracting its right armatures, relay 15 establishes a sclt-interruptingr circuit for motor magnet 1T extending from grounded battery` winding, armature and hack contact of said maf:- net, middle lower armature and bach contact ot relay 1G, 'frontv contact and inner right armature oi2 relay l5, brush 1S and trout contact and outer right aru'iature of relay 15 to ground. Magnet 17 operates to step the brushes from normal onto the set of terminals of the first trunk leading to a. succeedingswitcli. lf this trunk is busy, this condition is denoted Aby ground .upon the terminal engaged by brush '18 and this ground will be extended throughthe inner right armature and front contact 'ot relay' 15', the back contact and middle lower an mature of relay 16 to one endet the winding of said relay. The ground uponthc outer right armature and iront contact of relay .l5 is extended to the other end ol the wind-` ine` oi' relay 16 4and this relay is Ithereby shuntcd and prevented from operating.

Motor magnet i7 will thereforecontinue lo operate orer the previously described circuit until the terminals ot an idle'trunk are reached. .Y\.t this time no ground being;r on the terminal engaged by brush lS the shunt for relay 1G will be removed and this relay willvenergize over a circuit extended from grounded battery, winding` armature and `back contact ot' magnet 11T. windingr of revlay 16 and vtrentcontact und outer right armature of relay 15 to ground. Magnet 17 is 'adjusted so as not to operate in this circuit. The ground upon the outer right armatllre oli rela.)y 'I5 is now 'cxte'nded vthrough the innermost lower armature and trent contact of relay ltliand brush 18 to trunk and this `ground l'nain'tains 'the trunk in this condition untilrelay 15 is released. ARelay 16 is also locked up to this `ground through its winding` innermost lower armature and 'trent rtmtact. The energizzltion of relugY 16 opens 'the original ienergizing; circuit for f lay lli this relayY pulsi Atrein the rallinlc substatioii and :umn the 'st oiiennln ot i ircuit 'lor line reand in :so docalling); line throzugh the ing, extends the y bach contact and lett armature tliereol The lett winding of relay 15 is now shorten cuited and this relay will not energize again. llilhen relay 15 deenergrizes, the ound is removed ntrom the outer rie-ht arm Juro and 'liront contact, thereofl?, wliereupon the seized trunk will be held busy at the selector switches. lt will thus be apparent that the seized trunk leading;V to the selector switch is maintained busy by the line switch until the first impulse is transmitted trom sub station 1li,

Upon the first step o'l the switch troni its normal position a lground. is continuously applied to brush 21 ot' the switch. until the saine restored to normal, which ground will be applied to the test terminal 22 ol.l the connector multiple and. thus prevent seizure of the line ot substation 1li byan incoming call. y

It the service of substation 14E is restricted, brush 23 ol the switch is connected to front contact of the outermost lower armature oft relay 16 so that the ground at said armature wil l. be extended through briiish to means, not shown, at the succeeding; switch which will be energized to prevent the establishment of a call.

At the termination oit a call :from substation 11i, the release of the selector switch, to whicl'ijthe line switch is connected in a manner well known in the art, will remove ground 'irom the test terminal engaged by brush 18 and thus open the .lockingcircuit for cutofl:1 relay 16 which then deenergizes. A circuit is then established for motor in agnet 17 extendiiiig from grounded battery, winding, armature and back contact of said magnet, middle loweil armature and back contact oit relay 16, brush 2li, and the terminal engaged thereby, and back contact and outer right armature ot relay 15 to `ground. The magnet 1i' operates to step the brushes ofthe switch over the associated terminals until the switch is restored to normal.

Assuming that substation 14lis idle when an incoming call established through the connector multiple, a ground :troni a connector switch. upon the test terminal is exnassaui,

tended troni. hr1 4li al, normal lerniinal thereVH oli', winding; olli culioli' relay lo, buch ccnl; rt, armature and windinp,` oi' motor magnet li' to ,igi'ouiclcd hutte/Wy. ,llelay ll will energize and thus prevent energiaation ot Yline when the i-iuliscriber at substation l-li' spends to the incominev call hy rei'nox'iup,` h receiver from the swiiclihoolr. iliould the incoininp,l call be established manually by the ii'isertifin oli a plug` into jack ,25, the nroiiind applied to contact 215 will operate in the same n'iunner es that aijiplieiil to termi naV fl'l.

lillhat is claimed is:

l ln a telephone system a subscriliers sul sta ion including an impuls-se sending' de vice `thereat, a telephone line extending?,1 'from said substation, a plurality oit other lines, an automatic switch tor seizing` one of said other lines and interconnecting,` the same with said telephone line, means at said automatic switch for holding the seized line busy until ysaid impulse sending; device is operated, and means at a succeeding; switch for thereafter holding said seized line busy.

2. In a telephone system, a subscribers substation includingan impulse sendingr device thereat, a telephone line extending from said substation, a plurality ot other lines, an automatic switch 'for seizing one of said vother lines and interconnectingiF the same with said telephone line, means at said automatic switch for holding the seized line busy until said impulse sending device is operated, and means at said automatic switch for removing the busy condition thereat when the iirst impulse is transmitted by said sending device.

3. In a telephone system, an incoming line, a plurality of outgoinglines, an automatic switch lor seizingr one oil said outgoing lines and interconnecting the same with said incoming line, a relay at said aue tomatic switch arranged when operated to hold the seized outgoing line busysubse quent to the seizure thereof and means responsive to the transmission oi impulses over the incoming line for causing` the release of said. relay.

lla

4C. In a telephone system, a subscribers substation including); an impulse sending device thereat, a telephone line extending` from said substation, a plurality of other lines, an automatic switch 'l'or seizing' one oil said other lines and interconnecting the same with said telephone line, a relay at said automatic switch for holding' the seized line busy until said impulse sending,- device is operated, and means at a succeeding; switch for thereafter holding` said seized line busy.

5. In a telephone system. an incoming line, a plurality oi outgoinn1 lines, an automatic switch ttor one ot said outgoing lines and. intercrmnectingI the same with e lia Elv said incoin-ngline, a cutof relay for said switch, means for preventing operation of said cuto' relay upon the seizure of said outgoing 'linea-nd means yresponsive to impulses subsequently` sent over the incoming line forcausing the operation of said relay.

6.1`In a telephone system, a subscribers v'substation includingan impulse sending de- `vice thereat, a ltelephone line extending 10,

from ksaid substation, a plurality of other lines, an automatic switch for seizing` one of fsald other hnes and interconnecting the same with said: telephone line, a cutoff relay for said switch', and-means iorpreventing` operationrof said cutof relay until said irnpulse sending 'device is operated.

7. In a telephone system, a subscribers substation including an impulse sending device thereat, a telephone line extending from said substation, a pluralit of other lines, an automatic switch for seizing one of said, other lines and interconnecting the same with said telephone line, a cutol relay for said switch, a line relay for preventing operation of said cutoff relay subsequent to the seizure of said line and for holding said line busy until said impulse sendin device is operated, and means at a succee ing switch for thereafter holding said line busy.

In witness whereofj I hereunto subscribe my name this 4th day of August A. D. 191.9.

BERT G. DUNHAM. 

